World`s biggest source of spam e-mails shut down

London: The world`s most prolific source of spam e-mails -- an international network of virus-infected computers -- has been shut down in a series of coordinated raids by Microsoft and US federal authorities.

The Rustock botnet had for years generated billions of e-mails per day, promoting unlicensed online pharmacies and cut-price anti-impotence pills. A botnet is a collection of software agents that run autonomously and automatically.

But early last week, security firms noticed that e-mail traffic from Rustock completely collapsed, the Telegraph reports.

The scale of the shutdown is unprecedented. A report last month by SecureWorks, a computer security firm, said Rustock was the world`s biggest source of spam.

It has now been revealed that Microsoft, backed by US marshals acting on a court order, seized servers that it`s estimated covertly controlled almost a million Windows PCs.